Electric switch



ELECTRIC SWITCH 3 Sheets-Shea?J l Filed Nov. 17, 1951 ff a f4 f! i;

Dec. 29, 1953 P, R, GOUDY ET AL 2,664,482

ELECTRIC SWITCH Filed NOV. 17, 1951 3 Sheets-Sheet 2 Dec. 29, 1953 P. R. GoUDY ET AL ELECTRIC SWITCH 5 Sheets-Sheet 5 Filed Nov. 17, 1951 w IH:

Patented Dec. 29, 1953 UNITED STATES PATENT CFFICE ELECTRIC SWITCH Paul Goudy and Kenneth G. Sedgwick, Milwaukee, `Wis.,

assignors to Square D Company,

Detroit, Mich., a corporation of Michigan Application November 17, 1951, Serial No.f256,856

(Cl. 20G-124) tric switch having an improved and reliable Aoperating mechanism.

Another object of the invention is to provide an improved automatic manually operated electric switch having fixed and movable contacts, the movable contacts being slidably ,mounted within the base, While the iiXed contacts are snapped into position on the vbase to cooperate With the movable contacts.

Another object of the invention is the *provision of an electric switch in accordance with the preceding object in which the line-:l contacts are integral with circuit terminals.

Another object of the invention is the provision of an electric switch in accordance with the preceding objects in which an insulating cover, which is provided about the iixed contacts, is mounted to the main base by being snapped into Y position.

Another object ci the present invention is Vthe provision of an electric switch having an improved mounting arrangement for the movable and xed contacts whereby access to these contacts may readily be had.

Other objects and features of the invention will be readily apparent to those skilled in the art from the specincation and appended drawings illustrating certain preferred embodiments in which:

Figure 1 is aplan view of the'electric switch according to the present invention.

Figure 2 is a sectional view along the lines i-II of Figure l.

Figure 3 is a detail sectional view along the lines III- III of Figure l.

Figure 4 is a sectional iV- IV of Figure l, being shown in the parts being ing.

Figures 5 and 6 are views similar to Figure e, in which the operating parts are shown in the ed and tripped positions, respectively.

Figure 'i is a sectional view along the line I-VII of Figure l.

Figure 8 is a detail sectional View line YJill- VIII of Figure 1.

Figure 9 is a detail sectional view showing an intermediate step in the method of mounting the fixed contacts to the base.

Figure 10 is a rear View ofthe contact chamber View along the lines the operating mechanism on position, Ycertain o the broken away to facilitate this showalong the with part of the cover broken away to show internal parts.

Figure 11 is an exploded view of the operating mechanism of the present invention.

The electric switch, according to the present invention, comprises a molded, Bakelite base l to which a metal frame 3 is lxedly mounted by screws 2. The frame 3 has depending side plates 4 projecting toward the interior of the base l. A manually operated handle 5 is pivoted upon a pin extending between, and through suitable apertures in, the side plates The underside of handle 5 is provided with a slot 5 within which operates a pin l which is iXedly mounted to the upper portion of a spring lever 8. The spring lever fi has upper ears il which, when lever '8 is in mounted position, straddle opposite sides oi the under portion ci handle 5 Within the side plates 4. The spring lever S is pivotally mounted within the side plates 4 bymeans of pins Il, which project outwardly from the spring lever 8, and slots l2 provided inthe rlower portions of the side plates 4. A tongue I3 depends from the lever S, and is provided `with a suitable hole I4 through which extends 'one hooked end of an operating spring I5.

YThe opposite hooked end of the spring i5 is mounted to one end I6 or" an actuating lever Il, which has riveted thereto an insulating extension I8. VProjecting outwardly from opposite sides ofthe actuating lever l', are a 'pair of pins I9 which are disposed within suitable slots 2| of an overload lever 22. This overload lever 22 is mounted pivotally by means of a pin to the side plates l. of the frame 3. The upper end or lever 22 is provided with ears i@ which also straddle opposite sides of the under portion portion of handle 5, within the side plates As may be seen more clearly from Figure 3, to the overload lever 22 there is rlxedly mounted by rivets an insulating piece 23 to which, in turn, there is riveted a metal latch 2li. The overload mechanism which normally holds the latch 24 in a predetermined position is mounted to the base I by means of a screw 2&3, and coinprises a cup 2i within which is disposed a shaft 2T, the outer end of which carries a ratchet wheel 28. Within the cup 2G and disposed between its interior surface and the shaft 2l is disposed a relatively low melting point alloy in conventional manner, which in solidified condition prevents rotation of the ratchet Disposed about the cup 25 is an insulating spool 2S which carries turns of a resistance heating I element 3|.

One Vend of the resistance heating element Si Ascrew which is provided in a 'connector unit 32 of conducting material, which is mounted to the base l by means of a rivet rhe opposite end of the resistance heating element 3i is connected to a screw tt which is provided in the upper end of a generally U-shaped terminal contact member rlhe device of the present invention is provided with iour identical terminal-contact members 3d, each oi which, as will readily be seen from Figure 9, comprises a generally U-shaped section of conducting material to the interior end of which there is xedly mounted an electrical contact 35, while the upper end is provided with a threaded hole in which a terminal screw Sii operates. At opposite sides of each of these threaded holes there are provided in the terminal-contact member it lanced ears 3l. As may be seen from Figure 8, the molded base i is provided with suitable slots 38 positioned so that the ears 3l nt therein when the terminal-contact members 3ft are in position. Figure 9 shows that member Se is mounted to base l by engaging the base i with the contact end of member Sli, force then being applied to the terminal end of member Sli whereby ears 3l are forced inwardly toward slots 3S, into which they iinally move, the inherent resiliency ci member Sii maintaining this position. Disposed about these terminal-contact members til is a U- shaped, molded Bakelite cover 3S! having integrally molded, inwardly facing nubs iii. The legs of cover 39 are spaced apart a distance such that these nub-s il force the legs to spread outwardly when cover 3@ is forced to engage the base. When cover 3S has been moved to its proper position, however, the numbs lli project over ledges i2 of the base l, whereby the cover 52 is held in position about the terminal-contact members Se by means of its inherent resiliency.

As may be seen in Figure l0, the interior section of the base l is formed into three dinerent chambers by a pair of insulating walls 135 integral with the base l. These walls i5 are provided with slots fit, and aligned therewith are slots il formed in the opposite side walls of the base i. Within these slots lie and il there is disposed a rectangular, movable contact carrier i8 of insulating material. As may be seen from Figure 7, the carrier t8 is provided with a pair of spaced openings l5 through each of which extends a double ended movable contact ringer lil, a spring 52 being disposed within each of the openings #it to bias the ngers di toward the position illustrated in Figure 7. The lingers y5i are of conducting material and carry at each end an electrical contact 53. Centrally disposed within the carrier 43 is another opening 5t through which projects one end of the extension i3 of the actuating lever il.

The operation of the device will now be described. When the handle 5 is rotated in a clockwise direction from the position oi Figure 4, the spring lever ii is rotated in a generally counterclockwise direction about its pivotal connection with slot l2 by virtue of the pin islot e connection between the spring lever t and the handle 5. The end of operating spring l5 connected to the spring lever S is thereby carried downwardly from the view of Figure 4, and the spring I5 is progressively stressed as this movement of the operating handle continues. When the movement has progressed to the position in which the lower end of the spring l5 has passed the pin lil-slot 2l connection. so that the lill@ Of OIQIB of the spring i5 is below the point oi the pivotal connection between the actuating lever Il and the overload lever 22, spring l5 will eiect a rapid pivotal motion of the parts to the position of Figure 5. It will be seen that in this position, the extension i8 of the operating lever il has moved the movable contact carrier d8 outwardly, whereby the movable contacts 53 are separated from the fixed contacts 35.

With the parts in the off position as illustrated in Figure 5, as the handle 5 is rotated in a counterclockwise direction, the spring lever El is carried in a generally clockwise direction about its pivot in the slot i2, carrying the end of the spring l5 attached thereto upwardly (from the view of Figure 5) until its line of force is above the pivotal connection between the actuating lever il and the overload lever 22. When the line of force of the spring has passed this point, spring i5 will effect a rapid pivotal motion of the actuating lever il about its pivot in the slot 2l, the extension ld of the actuating lever i7 carrying the movable contact carrier dt rapidly inwardly within the slots and lil until the parts are in the position indicated in Figure 4, the movable contacts 53 bridging the Xed contacts 35.

Should an overload occur, when the overload current flows through the heating element 3i, the alloy within the cup 2t melts. The force exerted upon latch 255 by the spring i5 will thereby force the latch 2i to rotate the ratchet wheel 28 and become free therefrom, the overload member 22 to which the latch 2d is mounted being rotated in a clockwise direction about its pivotal connection in the side plates l or the frame S. As the pin lil-slot 2! connection is moved across the line of force of the spring i5, spring i5 will effect a clockwise rotation of actuating lever il about its pivotal engagement in the slot l2 until it reaches the position shown in Figure 6. In thus moving, the upper end it of the actuator Il has moved below the pivot II-slot I2 connection between the spring lever 3 and the frame 3. In this position the spring i5 forces the tongue i3 ci spring lever 3 to move downwardly from the position shown in Figure e to the position shown in Figure 6, rotating the spring lever 3 counterclockwise about its pivotal connection with frame 3 and by virtue of the pin l-slot 6 connection with the handle 5 also causing the handle to move in a clockwise direction about its pivotal connection with frame 3 until it assumes the indicating tripped position intermediate the on and oii positions, las shown in Figure G. As the actuating lever l1 rotates, the extension i5 thereof carries the movable contact carrier :i3 outwardly within the slots l5 and el to move the movable contact fingers 5! away from the fixed contacts. As may be seen from Figure 6, as a result of these movements, the ears 9 of the spring lever 8 `are engaged by the ears i@ of the overload lever 22.

After the alloy has suiiiciently cooled so that the ratchet wheel 233 is no longer rotatable, the parts may be returned to the manual control. This is effected by rotating handle E from the position of Figure 6 in a clockwise direction whereby the ears t of spring lever engaging the ears lli of overload lever 22, force lever 22 to rotate in a counterclockwise direction about its pivot in the frame. As this movement is efiected, the latch 2d is moved downwardly from the position. of Figure 6 past the ratchet wheel vboth the'ixed-an'd fby they may 4be leasily' changed: or vcleaned :as the 23, sothat'fwhenfhandle is released, ilatchf24 will move slightly upward .--torengageonelofthe teeth-J of'` ratchet" .wheelf"8. The. .latch.24:.is then wield vbythe .ratchet vwheel 28 .ini the position :il- .lustratedf .in Figure .5, .which Lalso 'shows .theiposition or the yother .partsafterithis.resetting ioperation hasfbeenfeifected. .The switch'r'may then again Vbe manually :opera-ted .as described .above, .until ffurther overload zoccurs.

ltf-.vfillibezseen -thatthe device of theipresent .invention is'bothrsturdyiand reliableiand operates with :a zquicl; *make aand vva .'qui'c'lr` break laction. It'yvill further be see-nithatlthe :device is trip-free. In addition, structural. arrangement providing for snapping 'on fiend: ycfffof the terminal-contact .members '34, Yand the snap von'connection :of cover '39,11together withthe lfree -sliding 4mounting of v.the movable `.Contact carrier 48 makes the :device inexpensivetovassemble,xand provides for .ready accessibility to the movable contacts Where- 'occasionY arises.

Whilecertainpreferred embodiments of the :invention have beenspecically disclosed, it is vunderstood that :the .thereto, as :many lvariations will `parent tothose skilled in the art and the=inveninvention is lnot limited be readily apmeans to openand closed `circuit positions, an

insulating -base lenclosing .said `actuating and :movable'contact means, conducting'xed contact means vof substantially resilient metal 'and generally U-shape disposed .at opposite sides of s said basefwiththeopposing leg, portions of said fixedy contact ymeans tightly engagingA upper 4and lowerfsurfaces of said base whereby said xed contact means are held imposition by the resiliency of said fixed contactmeans, and a vgen- -erally U-shaped cover of insulating material disl posed about said -iixed contact means, vopstanding portions of .said cover spaced apart a distance substantially equal to the widthoi said base, and `interengaging distorted portions on said upstanding portions and said base whereby said cover is mounted to said base only by the resiliency of said cover.

2. In electric switch having actuating means operable to effect opening and closing of an electrical circuit through the switch, movable contact means-.operable by said actuating .means rtoppen and closed circuit positions, an insulating base enclosing said .actuating and movable contact means, conducting fixed contact means of Vsubstantially resilientmetal and generally .U-shape disposed at opposite sides of said base, .an .electrical contact mounted to one leg of said U, terminal means in the other leg of vsaid .U, the opposingleg .portions of said xed contact means tightly engaging upper .and `lower surfaces of said-basewhereby said iixed Contact .means are held in position by the resiliency of said xed contact means, and a generally U- shaped cover or" linsulating :material disposed about said xed contact means, upstandingporytions of said cover spaced apart a distance substantiallyequal to `the width of said base, and interengaging .distorted portions on said up- .stan'ding portions and said base Awhereby .said

Hoover. islimounted to said base only by the resiliv'1ency iof saidzcover.

.f3.'In :an electric switch having actuating `means `-operable'to'efect opening `and closing of -anzelectricalicircuit through the switch, movable contact means operable by said actuating 'meansto' open'iand closed circuit positions, an

insulating base enclosing said actuating and conducting.zxed contact means oi substantially resilient Vmetal and l.generally U shape disposed at opposite sides or said base, the opposing leg portions of' said fixed contact means tightly engagn ing upper and lower surfaces of said base where- 'bysaid fixedV contact means are held in position yby -the resiliency lof Vsaid iixed contact means, 'and a .generally U-shaped cover of insulating material disposed labout said listed contact .meansupstanding portions of said cover spaced apart a distance substantially equal to the width -of vsaid hase, and interengaging distorted portions .onsaidupstanding portions and said base whereby-said cover-is-mounted to said base only by the resiliency of saidcover.

.4. In van electric switch having actuating .means .operableto effect opening and closing of electrical circuit through the switch, an insulating base having side walls and at least a portion having an open bottom, a pair oi spaced insulating .barriers within said base portion parallelingsaidside walls and dividing said base portion into three chambers, slots extending through said barriers,.movable contact within said slots comprising a carrier with spaced .contacts thereon, each of said contacts extendinginto a separate chamber, means o perated by said actuating means for moving said movable contact means to open and .closed circuit positions, and xed contact means of substantially resilient metal .and generally U shape disposed at opposite sides oi said base, one of the legs of said U tightly engaging an upper surface of said base while the ot er leg tightly engages a lcwersurface of said base whereby said xed Contact means are positioned on said base by the 'resiliency of said fixed contact means.

5. In an electric switch having actuating means operable to eiect opening and closing of an ele"- trical circuit through the switch, insulating base having side walls and at least a portion having anopen bottom, a pair of spaced insulating barriers within said base portion paralleling said side Walls and dividing said base portion into three chambers, slots extending through said barriers, movable contact means within said slots comprising a carrier with spaced .contacts thereon, each of said contacts extending into a separate chamber, means operated by said actuating meansior moving said movable contact Vmeans to open and closedcircuit positions, fixed contactmeans of generally U shape disposed at vopposite sides of said base, one of the legs of said U .tightly engaging-an upper surface of basewhilethe other leg tightly engages 'a lower surface of said .base whereby said xed .contact means are positioned-.on said base by the resiliency .of said xed contact means, and a U-'shaped cover of Vinsulating material disposed if about said fixed contact means, said cover having legs spaced apart a distance substantially equal to the width of said base, and interlocking portions on said legs and base whereby said cover is mounted to said base only by the resiliency of said cover.

6. In an electric switch having actuating means operable to effect opening and closing of an electrical circuit through the switch, an insulating base having side walls and at least a portion having an open bottom, a pair of spaced insulating barriers within said base portion paralleling said side walls and dividing said base portion into three chambers, slots extending through said barriers, movable contact means within said slots comprising a carrier with spaced contacts thereon, each or" said contacts extending into a separate chamber, means operated by said actuating means for moving said movable contact means to open and closed circuit positions, and fixed contact means of generally U shape djsposed at oppositesides oi said base, an electrical contact mounted to one leg of said U, terminai means mounted to the other leg of said U, the terminal carrying leg tightly engaging an upper surface of said base while the other leg tightly engages a lower surface oi' said base, and interlocking portions on at least one of the legs and on the base whereby said xed Contact means are positioned on said base by the resiliency or" said fixed Contact means.

'7. In an electric switch having actuating means operable to effect opening and closing of an electrical circuit through the switch, an insulating base having side walls and at least a portion having an open bott in, a pair of spaced insulating barriers within said base portions paralleling side walls and dividing said base portion into three chambers, slots extending through said barriers, movable contact means within said slots comprising a carrier with spaced contacts thereon, each of said contacts extending into a separate chamber, means operated by said actuating means ior moving said movable contact means to open and closed circuit positions, 'fixed contact means of generally U shape disposed at opposite sides of said base, an electrical contact mounted to one leg ci said U, terminal means mounted to the other leg of said U, the terminal carrying leg tightly engaging an upper surface of said base while the other leg tightly engages a lower suriace ci said base whereby said iixed Contact means are positioned on said base by the resiliency of said nxed contact means, a U-shaped cover ci insulatin y material disposed about said fixed `contact means, said cover having legs spaced apart a distance substantially equal to the width of said base, and interlocking portions on the interior of said legs and the base whereby said cover is mounted to said base only by the resiliency of said cover.

8. In an electric switch, an insulating base, a frame, an operating handle pivoted in said frame, a first lever pivoted in said frame and in said handle, an overload lever pivoted in said frame, an actuating lever pivoted in said overload lever, an operating spring interconnecting said rst lever and said actuating lever, and thermal responsive means normally holding said overload lever in a predetermined position, movement of said rst lever by movement of said handle er" fecting movement of said spring across the pivotal connection between the actuating and overload levers whereby said actuating leveris rotated, and contact means operated by said actud ating lever to open and close the electrical circuit through the switch.

9. In an lelectric switch, an insulating base, a frame, an operating handle pivoted in said frame, a iirst lever pivoted in said frame, Va pin and slot connection between said handle and said nrst lever, an overload lever pivoted in said frame, an actuating lever pivoted in said overload lever, an operating spring interconnecting said first lever and said actuating lever, and thermal responsive means normally holding said overload lever in a predetermined position, movement of said iirst lever by movement of said handle effecting movement or said spring across the pivotal connection between the actuating and overload levers whereby said actuating lever is rotated, and contact means operated by said ac tuating lever to open and close the electrical circuit through the switch.

10. In an electric switch, an insulating base, a frame, an operating handle pivoted in said frame, a first lever pivoted in said frame, a slot in said handle, a pin on one end or" said first lever cooperating with said handle slot whereby rotation of said handle eiects rotation oi iirst lever, an overload lever pivoted in said frame, an actuating lever pivoted in said overload lever, an operating spring connected to the opposite end of said nrst lever and to said actuating lever, thermal responsive means, and means on said overload lever normally engaging said thermal responsive means whereby said overload lever is retained in a predetermined position with the pivotal connection of said actuating lever therein substantially in alignment with the pivotal connection or" said rst lever in said frame, rotation of said handle in a irst direction efecting rotation of said iirst lever in the opposite direction whereby said spring is moved across the pivotal connection of the actuating lever in the overload lever and thereby eiects rotation or the actuating lever, and contact means operated by said actuating lever to open and `close the electrical circuit through the switch.

ll. In an electrical switch, an insulating base, a frame, an operating handle pivoted in said frame, a lever pivoted in said frame, a slot in said handle, a pin on one end of said lever cooperating with handle slot whereby rotation of said handle eiects rotation or said nrst lever, an over-- load lever pivoted in said frame, actuating lever pivoted in said overload lever, operat spring connected to the opposite end of said fhst lever and to said actuating lever, and mams reM sponsive to overload current flow through switch for normally retal ing said overload lever in a predetermined position, said last n tioned means releasing said overload lever in response to overload current flow wher by said overload lever is rotated in said frame and carries the pivot oi said actuating lever across operating spring to eiiect a rapid pivotal movement of said actuating lever, and contact means moved by said ctuating lever to open circuit position.

l2. In an electric switch, an insulating base, a frame, an operating handle pivoted in said a f rst lever pivoted in frame in sa handle, an overload lever pivoted in said iframe, an actuating lever pivoted in said overload lever, an operating spring interconnecting nrst lever and said actuating lever, and thermal responsive means normally holding said overload lever in a predetermined position, movement of said iirst lever by movement oi said handle effect ing movement or" said spring across the pivotal connection between the actuating and overload levers whereby said actuating lever is rotated, fixed contacts, and movable contact means for cooperation therewith comprising an insulating plate with movable contacts mounted thereto, said actuating lever effecting movement of said movable contacts toward and away from said xed contacts.

13. In an electric switch, an insulating base, a frame, an operating handle pivoted in said frame, a rst lever pivoted in said frame and in said handle, an overload lever pivoted in said frame, an actuating lever pivoted in said overload lever, an operating spring interconnecting said iirst lever and said actuating lever, and thermal responsive means normally holding said overload lever in a predetermined position, movement of said rst lever by movement of said handle eifecting movement of said spring across the pivotal connection between the actuating and overload levers whereby said actuating lever is rotated, spaced xed contacts, movable contact means for cooperation therewith comprising an insulating plate having spaced contacts thereon, and slots within said insulating base guiding said insulating plate for rectilinear movement, said actuating lever havng a lost motion connection to said plate for effecting movement of said plate within said slots to open and close the electrical circuit through the switch.

14. In an electric switch, an insulating base, a frame, an operating handle pivoted in said frame, a first lever pivoted in said frame and in said handle, an overload lever pivoted in said frame, an actuating lever pivoted in said overload lever, an operating spring interconnecting said iirst lever and said actuating lever, and thermal responsive means normally holding said overload lever in a predetermined position, movement of said rst lever by movement of said handle effecting movement of said spring across the pivotal connection between the actuating and overload levers whereby said actuating lever is rotated, xed contact means of generally U shape disposed at opposite sides of said base, the opposing leg portions of said fixed contact means tightly engaging upper and lower surfaces of said base whereby said fixed contact means are held in position by the lresiliency of said fixed contact means, movable contact means for cooperation therewith comprising an insulating plate having spaced contacts thereon, and slots within said insulating base in which said insulating plate operates, said actuating lever eifecting movement of said plate within said slots to open and close the electrical circuit through the switch.

15. In an electric switch, an insulating base, a frame, an operating handle pivoted in said frame, a first lever pivoted in said frame and in said handle, an overload lever pivoted in said frame, an actuating lever pivoted in said overload lever, an operating spring interconnecting said first lever and said actuating lever, and thermal responsive means normally holding said overload lever in a predetermined position, movement of said iirst lever by movement of said handle effecting movement of said spring across the pivotal connection between the actuating and overload levers whereby said actuating lever is rotated, xed contact means of generally U shape disposed at opposite sides of said base, an electrical contact mounted to one leg of said U, terminal means in the other leg of said U, the opposing leg portions of said xed contact means tightly engag- Ait) ing upper and lower surfaces of said base whereby said fixed contact means are held in position by the resiliency of said nxed contact means, movable contact means for cooperation therewith comprising an insulating plate having spaced contacts thereon, and slots within said insulating base guiding said insulating plate for rectilinear movement toward and away from the stationary contacts, said actuating lever having a sliding connection to said plate for eifecting movement of said plate within said slots to open and close the electrical circuit through the switch.

16. In an electric switch, an insulating base, a frame, an operating handle pivoted in said frame, a first lever pivoted in said frame and in said handle, an overload lever pivoted in said frame, an actuating lever pivoted in said overload lever, an operating spring interconnecting said first lever and said actuating lever, and thermal responsive means normally holding said overload lever in a predetermined position, movement of said rst lever by movement of said handle eifecting movement of said spring across the pivotal connection between the actuating and overload levers whereby said actuating lever is rotated, xed contact means of generally U shape disposed at opposite sides of said base, an electrical contact mounted to one leg of said U, terminal means in the other leg of said U, the opposing leg portions of said xed contact means tightly engaging upper and lower surfaces of said base whereby said xed contact means are held in position by the resiliency of said fixed contact means, movable contact means for cooperation therewith comprising an insulating plate having spaced contacts thereon, slots within said insulating base in which said insulating plate operates, said actuating lever effecting movement of said plate within said slots to open and close the electrical circuit through the switch, and a generally U-shaped cover of insulating material disposed about said xed contact means, said cover having upstanding portions spaced apart a distance substantially equal to the width of said base and interlocking with the base whereby said cover is mounted to said base only by the resiliency of said cover.

17. In an electric switch having actuating means operable to eifect opening and closing of an electrical circuit through the switch, movable contact means operable by said actuating means to open and closed circuit positions, an insulating base enclosing said actuating and movable contact means, one portion of said base having side walls and an open bottom, conducting fixed contact means of generally U shape, an electrical contact mounted to one leg of said U, a threaded hole and distorted portions in the other leg of said U, a screw in said threaded hole, a distorted portion in said base on the top of said side walls cooperating with said leg distorted portion and a portion of said side wall adjacent said open bottom engaging said one leg of said U, whereby said iix'ed contact means are mounted to said base by the inherent resiliency of said fixed contact means.

PAUL R. GOUDY. KENNETH G. SEDGWICK.

References Cited in the le of this patent UNITED STATES PATENTS Number 

